1. Field of the Invention
The invention relates to a light guide plate, and more particularly to light guide plate with optimal light output efficiency.
2. Description of the Related Art
Liquid crystal displays (LCD) are widely used in consumer electronic products, such as personal digital assistants (PDA), mobile phones, digital cameras, notebook computers, desktop monitors and automotive displays, due to advantages of high image quality, small size, light weight, low driving voltage and low power consumption. An LCD includes a liquid crystal panel at a front side and a backlight module at a rear side thereof. The backlight module may be of edge light type or direct light type. The edge light type backlight module usually includes a light guide plate and a plurality of light emitting diodes (LED) disposed at a side of the light guide plate. The light guide plate converts point light emitted by the LEDs into uniform planar light, thus forming a planar light source required by the LCD.
Recently, LCDs are required to have a slim bezel, resulting in smaller distance between the light guide plate and the LEDs for mixing light emitted by the LEDs, so as to induce hot spots at an edge of the light guide plate proximate to the LEDs in a form of alternating bright and dark regions or jet-stream shapes. In order to solve the hot spot issue, some conventional designs, as shown in FIGS. 1 and 2, have proposed to form, on a light entry surface 11 or a light exit surface 12 of the light guide plate 1, a light guide structure 13 including a plurality of elongated elements 131 disposed side by side, and each of the elongated elements 131 has a cross section in a shape of a circular segment. In another conventional design as shown in FIG. 3, the light guide plate 2 has a light guide structure 23 formed on a light entry surface 21 thereof and a light guide structure 24 formed on a light exit surface 22 thereof. The light guide structure 23 includes a plurality of elongated elements 231 disposed side by side, and each of the elongated elements 231 has a cross section in a shape of a circular segment. The light guide structure 24 includes a plurality of triangular prisms 241 disposed side by side.
However, further improvement in light uniformity and light output efficiency at different angles is still desired.